Nongrounded or metallic line-circuit system



May 26, 1925.

R. H. BURFEIND NONGROUNDED OR METALLIC LINE CIRCUIT SYSTEM Original ileApril'ls, 1907 5 Shests$heet l t1usnImr f B mcmU'HBurTE'z cf May 26,1925.

Re. 16,086 R. H. BURFEIND NON-GROUNDED 0R METALLIC LINE CIRCUIT SYSTEM 3Sheets-Sheet 2 Original Filed April 18, 1907 Jnueniur R. H. 'B RFEINDNON-GROUNDED OR METALLIC LINE CIRCUIT SYSTEM Original Filed April 18,190? 3 Sheets-Sheet 3 Reissued May 26 1925.

UNITED I STATES mmoma H. num'nmn, or cmcaoo, rumors, asslsnoa, BY misun-ASSIGNMENTS,

TO AUTOMATIC ELECTRIC COMPANY, A CORPORATION OF ILLINOIS.

NONGBOUNDED OB METALLIC LINE-CIRCUIT SYSTEM.

Original in. 1,299,119, dated April 1, 1919,8612 no. 369,021, med April18,1907. Application for reissue fled August 80, 1920. Serial No.407,038.

To all whom it may concern:

Be it known that I, RAYMOND H- BUR- FEIND, a citizen of the UnitedStates of America, and resident of Chicago, Cook County, Illinois, haveinvented a certain new and useful Improvement 3 in Nongrounded orMetallic Line-Circuit Systems, of which thefollowing is a specification.

Myinvention relates to automatic telephone systems in which means areprovided for enabling a' calling subscriber to extend his line intoconnection with the line of the called subscriber, or into connectionwith some other, line, without the aid of operators. 1 v

The principal object of my invention is therovision of an improvedsystem in which the apparatus at the exchange or central station may" becontrolled by the callin subscribers, for the purpose of establis ingconnection with the lines of the called subscriber, or for the purposeof disconnecting a'nd restorin the automatic switches after thesubscribers are through talking, without employing operating withoutemploying ground circuits between the substations and thecentralstation.

It is also an object, of course, to provide certain details .andfeatures of im prover'nent and combinations tending to increase thegeneral elficiency and serviceability of an automatic tele hone exchangesystem ofthis particular c aracter.- v

- In application No. 369,013, filedApril 18, 1907, by A. E. Keith forimprovement in non-grounded or metallic circuit systems,a system isshownin which the switches are operable, without the necessity of usingground connections at the-subscribers stations. Also, in applicationSerial No. 369-,-

-012, filed April 18, 1907, by E. AQMellinger,

a system is shown in which a plurality of automatic switches aresuccessively controllable or operable .without using 'grounds at thesubstations, and these switches are also releasable; in the same manner.My

present invention is, therefore,'- in the nature of an improvement onthe s stems thus disclosed in t lin r applications. v

w n the accompanying drawings, Figures 1 and 2 taken together representdiagramt the substations-that is to say,-

e said prior Keit and Melmatically a calling substation A connected bymeans of central oflice switching apparatus with a called substation A,in a systemembodying the principles of my invention. The switches,through which the stations A and A are shown connected, comprise, inFig. 1, the so-called first-selector C and second-selector D; and inFig. 2,.

a connector E and a first selector C similar to the first-selector C.The selector C is individual to the line of the substation A, while thefirst-selector C is individual to the line'nof the substation A, #2220.

The said selectors Q and C are substantially thezsame in construction.For 'opcrating the central ofiice switches there is provided a centralsource of current or'bat ter B having its positive terminal preferalygrounded at G (Fig. 2).

Figs. 3, 4 and 5 are detail views of the I substation impulse springs.

Figs. 6, 7 and 8 are detail views ofv the release relays of the selectorand connector switches. 1 4

It will be understood, of course, that in thls'system thefirst-selectors are arranged in groups, as wellas the second-selectorsand theconnectors. -A somewhat common arrangement is to divide thesubstations.

into groups of one hundred, and to, of course, 'dividetheir' allottedselectors into corresponding groups. Furthermore, every groupof.first-selectors has allotted to it a group of second-selectors forevery-bank level. Through the medium of the second- -selectors theconnectors of various hu-ndred-groups are reached. The connectors andsecond-selectors are less in number than the subscribers-that is, theyare" employed ,on 'a' percentage basis. The substation may be of anysuitable or approved type. elected to illustrate my invention comprises7 The one in connection with which I have a receiver 2, switch-hook 3for controlling the substation circuits, which controlling dperationsareaccomplished through the medium of any suitable means, such as thecam-arms 4: and 5; ,When the switch-hook is down, thecam-arm 4 carriesthe s ring 6 out of engagement with the spring V and into engagementwiththe spring 8, thereby bridging the ringer 9 in series with thecondensers 10 and 10' across the line; Furtherand rotary impulse springs18 and 19. Said substation is, of course, rovided with a dial, which isnot shown ut which is securedto the shaft 20, together with the lockingdog 21. Furthermore, there is a. locking cam 22 that locks the dog 21,while v the receiver is on the switch-hook, to prevent a rotation of thedial. For operating the impulse springs18 and 19 (Fig. 3) the substationis provided with an im ulse wheel 23 that is secured to the sha' 20,

' which impulse wheel carries on its periphery'the so-called erticalimpulse eeth 24 and one rotary impulse tooth 25. .c said impulse teethare so arranged that when the dial is drawn down the impulse springs 18and 19 are not operated; but as the dial returns, first the verticalteeth engage the vvertical im ulse spring 18 (Fig. 4) and after theyhave completed their work the rotary impulse tooth 25 operates therotary impulse spring 19 (Fig. 5). In this operation the verticalimpulse spring 18 is pressed into contact with the spring 26, wherebythe vertical line conductor 27 becomes connected directly withthe rotaryline conductor 28 Normally, when the receiver is re moved, the verticaland rota line conductors 27 and 28 are connect through the highresistance coil 29. After the vertical impulse teeth have operated thevertical impulse sprin 18, the rotary impulse tooth 25 momentari ydisengages the springs 19 and 30, whereby the line conductors 27 and 28become separated; and when the springs engage, the line conductors 27and 28 are again connected through the coil 29. It will be clear fromthe drawings that when the subscriber rotates the dial the rotaryimpulse tooth 25, upon returning or rotating in a counter-clockwisedirection, meets the angled member shown on the end of the spring 19,pressing, as it advances, both springs 19 and 30 out of the way, butwithout breaking connection. However, when the dial returns towardnormal position the rotary impulse tooth 25 comes in behind the memberon the end of the spring 19, flexing the said spring 19 away from thespring 30, thus breaking the circuit as de, scribed. It will beunderstood, furthermore, that the shaft 20 is provided with a sprinadapted to restore the dial when once it as been rotated out of normalposition. Furthermore, the switch hook also provided with any suitablewhereby said switch hook may be caused to rise when the weight of thereceiver 2 is prises the push button 31, which, when pressed, carriesthe spring 32 into engagement with the contact point 33, whereby theline conductors 27 and 28 are connected.

The first-selector switch shown at C maybe of any suitable or approvedtype, for instance of the general type described in United StatesPatent-No. 815,321, granted March 13, 1906, to Keith, Erickson &Erickson. Among other details, it embodies the following well-knowndevices and circuits: The switch shaft 34 carries the vertical androtary wipers .35 and 36, respectively, and. the private wiper 37. Theside switch is well known and comprises the side switch wipers 38, 39,40, 41. and 42, which may be designated as the vertical, rotary and private side switch wipers, the rotary magnet wiper and release relaywiper, respectively. The side switch is under the control of the privatemagnet 43, and when the side switch is in normal or first position thewipers 38, 39, 40, 41 and 42 occupy the contact points 44, 45, 46, 47and 48, respectively. In the second position they rest on the contactpoints 49, 50, 51, 52 and 53, respectively, and in third position thecontact points 54, 55, 56, 57 and 58 are engaged by their respectivewipers. Through the medium of the vertical line relay 59, and while theside switch is in first position, the subscriber controls the verticalmagnet 60, which latter operates to raise the switch shaft 34 and wipers35, 36 and 37 'verticall By means of the rotary line relay 61, an beforethe shaft has rotated to disengage the springs 62 and 63, the subscribercontrols the private magnet 43, and, therefore, the side switch. Whilethe side switch is in. second position the rotary magnet 57*, whichoperates to carry the switch shaft and wipers 35, 36 and 37 in a rotarydirection, is energized. The relay 63 provides the means whereby thesubscriber controls the release magnet 64 while the side switch is inthe -first or second position, and while the switch lUI) gagement withthe spring 143 and into engagement withthe spring 32 thelatch 31 thenfalls over the end of the spring 32 and locks the two springs 32 and 142in contact (Fig. 7 'Now, when the relay 63 deenergizes, the two lockedsprings 32* and 142 are carried into engagement with the spring 143;then when the release magnet 64 energizes, the armature 33 is attractedand re the hitch Si in such that it turns about its pivot oints on theend of the spring 142 and un ocks the springs 142 and 32, whereby thetwo springs disengage. If the side switch passes to the third position,then since the selector C is of the trunkrelease type, the selectorthrough the next switch, and a connection with the latter isthenestablished through the private wiper 37 and by .means of theback-release rela 65. The bridge-cut-ofi relay 66 is provi ed to openthe connection between the line relays 59 and 61 and the batteryterminals. It will be noticed that the vertical line relay 59 isconnected to the non-grounded terminal, and that the rotary line relay61 is connected to ground. This disconnection is desirable, because ifthe relays are not disconnected from battery, the ringing current forsignaling the subscriber may then operate either or both of the relays59 and 61 and cause some interference with the switch. It is alsodesirable to remove the ridge formed through the said relays from acrossthe line so as to give the voice-currents as clear a path as possible.Furthermore, the shaft 34is provided with the cam 66 which, when theshaft is in normal position, permits the springs 62 and 63 to disengage;but on the first vertical step of the shaft 34 the cam 66 presses thesaid springs into engagement. a. Now when the shaft is given a rotarystep the cam 66 is carried out of engagement with the spring 63, and thesprings 62 and 63 disengage. The switch-shaft is provided with a normalarm 67 which, when the shaft is given a vertical im ulse, permits thespring 70, which normal y engages.

the spring 68, to pass into contactwith the spring 71. v

The second selector D is similar to the first selector C, with theexception that there are no normal conductors, such as the normalconductors 72 and 73. Since there is no use for such conductors they areomitted. There is also no utility in the second selector for a bridgecut o-fi relay, such as the relay 66 of theselector C, and this is alsoomitted, and the line relays are connecteddirectlyto the batteryterminals. The private normal conductorfsuch as the private normalconductor 74 of the selector G, is of no use in connection with thesecond selector and is also omitted. Since likeparts are similarlyrepresented throughout the drawings, the vertical magnet 75 and therotary magnet '76, the release magnet 77 and the private magnet 78 willbe recognized and understood. The said private magnet 78, of

course, controls the side switch wipers 79, 80, 81, 82 and 83. Thevertical movement of the switch shaft 84 and, therefore, of the wipers85, 86 and 87, is controlled by,the vertical magnet 75, and the rotarymovement by the rotary magnet 7 6, the'rotary magnet is controlledvshaft wipers their vertic circuit being provided with theusualfinterrupter springs 88. The operative magnets of the switch are,of course, controlled by the subscriber through the medium of thevertical and rotary llne relays 89 and 90, as is well known. Said relayshave under their control the usual springs 91, 92 and 93. The

selector D is also provided with a release relay 94 for controlling therelease of the switch when the side switch passes to third position. Therelay 95 controls the ener '2- ing circuit of the release magnet 77' w'le the side switch is in first and second posi tions and the shaft is011' normal. The release controlling relay 95 in the secondselectoroperates inlthe same'manner as the release relay 63 of thefirst-selector. If,

while the said switch of the selectorl) is in and moves the latch insuchmanner that it turns about its pivot points on the end of the spring 99and unlocks the and 102, whereby the two springs sengage. The camsprings 96 and 97 are" controlled by the shaft cam 98, in the samemanner in which the cam springs of the selector controlled.

C are springs 99 The connector switch E may also of} any suitable orapproved type, for instance of the general type described in UnitedStates Patent No. 815,17 6, granted March. a

13, 1906, to Keith, Erickson & Erickson. The mechanical details of thefirst-selector and connector, as is well known, are vei much the same.The connector switch sha t 104, like the first-selector switch shaft,car-.

ries the line wipers and 106 and the private wiper 107. The connectorswitch is also controlled b the calling subscriber through the medium ofthe vertical and rotary line rela s 108 and 109. The vertical line relaydirectly controls the vertical magnet 110, and also the rotary magnet111 and the ringer relay 112. The ofiice of the vertical magnet 110 isto give the shaft and a motion, and the rotary magnet 111 imparts to theshaft and shaft wipers a rotary or circular motion. The rotary linerelay 109 controls the energizing circuit of the release relay 113. Therelease relay 113 is similar to the relay 95 of'the second-selector, andwhen the relay 113 is energized the spring 129 is shifted out ofengagement with the spring 130 and into the locked springs 129 and Y131are carried into contact with the spring 130; but as the armature 133nears its normal position, the

latch 132 comes into contact with the beveled member 134, whereby thelatch 132 grad ually slides from the end of'the spring 131; and when-thesaid spring is unlocked it returns'to normalposition, outof engagementwith the spring 129. The private magnet 114 is controlled by. thevertical line relay 108, and under certain conditions controls therelease magnet 120 and also the side switch wipers 115, 116, 117,118and'119. The side switch of the connector, like the side switch of thefirst-selector, has a normal or first position, a second position and athird position. The release magnet 120 is also controlled by the relay121. By the condensers122 and 123 the circuit through I the connector isdivided into 'two' sections.

The central ofiice is equipped with busy-\ signaling apparatus of anysuitable desi n,

as, for example, the one comprising an 1nterrupter122' in series withthe primary winding 123 of the induction-coil 124, whereby abusy-signaling current is induced in the secondary winding '125 of thesaid coil. The connector switch shaft 104 also carries a normal t arm126 which, when the connector shailz is oif normal, allows the sprin 127to engage the contact point 128, wheriiy the busy-signal may betransmitted to the rotary line conductor. V

The substation A is like the substation A; also, the first-selectorswitch C allotted to the line #2220 is like the first-selector Callottedto the line #5000.

A clearer understanding of my improved stem ma be had from an exlanation of t e operatlon of the central 0 ce switches when onesubscriber calls another. Suppose, for an example, that the subscriberat substation A desires to communicate with the subscriber at substationA on the line #2220. The operation of the central oflice switches, tobring about this connection, is

soon as the sad springs 62 and 63 come into as follows: When thesubscriber at substation A removes the receiver 2.'from the switch-hook3 the cam-arm 4 permits. the

springs 7 and 6 to engage, whereby a series circuit including thevertical line rela 59 of the selector C, resistance-coil 29 o thesubstation A, and the rotary line relay 61 of the selector C is closed,This circuit extends from ground G at the selector C through the sprinthrough the resistance-coil 29 to the vertical line conductor 27, sideswitch wiper 38, con- 135 and 136, through. i the rotary line re ay 61,contact point 45,

side switch wiper 39, rotary line conductor 68 137 and 138 to thebattery lead 139, thence through battery B and to ground G. The rotaryline relay 61 is so adjusted that the current-flow is sufficient tooperatively energize the said relay, while the vertical line relay 59 isso adjusted that the current-flow in this circuit is not suflicie'nt tooperatively energize it. The rotary line relay, upon energizing, placesthe springs 140 and 141 in contact.- This closes a circuit through therelease controlling relay 63. The C11- cuit through the releasecontrolling relay extends from 1.41 and 140, t rough therelay 63 to thebattery lead l39,'thence through battery B and to ground G. This'relay,upon energizing, separates the springs 142 and 143, and places thespring 142 in contactxwith the spring 32*. When the dial is rotated forthe first digit 2 the spring 18 is twice pressed into contact with thespring 26. By this opera- .tion the line conductors '27 and 28 arediwhich does not include the resistance-coil 29, is established throughthe vertical and thus a new circuit,

round Gr through the springs I rotaig line relays 59 and 61 of theselector C. u

flicient current now flows in the circuit to operatively energize thevertical line relay 59, which latter, upon energizing, presses thesprings 144 and 141 into contact, which closes an energizing circuitthrough the vertical ma net 60. This circuit extends from ground 2through the springs 141 and 144, through the vertical magnet 60-to thebattery lead 139, thence through battery B and to ground being twicepressed into contact for the first digit, the vertical line relay 59 istwice oper- G. The springs 18 and 26 atlvelyenergized, and th'everticalmagnet is in turn energized twice. By this operation of the verticalmagnet the shaft 34 and the shaft wipers 35, 36 and 37 are raisedtwo-steps and brought opposite the second bank level. It should be bornein'mind that at the'first vertical step of the switch shaft the cam 66operates to ,closein contact the normally open shaft springs 62 and 63.As

contact an energizing circuit is established through the private magnet'43 from ground G at the selector C, through the springs 141 and 140,through the cam springs 62 and 63 to the private magnet 43, thencethrough said magnet to the battery lead 139, and through battery-B toground G. Furthers more, atthe. same first vertical step the normal post'arm 67 disengages from the spring 70, permitting the latter to leave"the spring and toengage with 71. This operation, of course, disconnectsthe grounded spring the private normalconductor 74 from the ,7

bridge-cut-ofi relay 66 and places a guarding potential 'on said privatenormal con- .the second level'wi ground, as is usually the custom insystems- 7 tion, thus causes private magnet ductor from ground Gr toprevent any calling subscriber from calling in upon theline #5000 afterthe switch C has been operated. The rotary impulse tooth 25 separatesthe springs 19 and 30, which open the circuit includingthe vertical androtary line relays and resistance-coil 29. The-rotary line relay 61,being deprived of its energizing current, de-energizes and permits thesprings 141 and 140 to separate, whereby the energizing circuit of theprivate magnet 43 is broken,

.and the side switch is permitted to pass to second position. As soon asthe impulse springs 19, an 30 again come into contact, and again theenergizing circuit through the rotary line relay is established. In themeantime, however, the circuit through the release controlling relay 63is broken, but the relay being a slow-actingrelay sufiicient residualmagnetismis retained in the core to maintain the relay manoperatedposltion until this energizing circuit is again established,when the rotary line relay energizes.

When the side switch passes to second position an energizing circuit.isestablished cuit' extends from the grounded" contact point 52 throughthe side switch wiper 41, interrupter springs 145, rotary magnet 57 tothe battery lead 139, thence through battactsof the second level: but ifthe first trunk lineis busy some other selector (similar to the selectorC) in the exchange will be resting in engagement vwith said trunk line,and the first rivate bank contact of H be found connected: to

of this general character. Therefore, when the selector shaft is rotatedone ste an energizing circuit is established throng the pnvate magnet43, when the. private wiper 37 I strikes thegrounded private bankcontact,

thereby retaining the side switch in second position and maintaining theenergizing (S1I'-' cult through the rotary 'magnetfl57'. The rotarymagnet, by. intermittent magnetizathe shaft to rotate step by step andcarry the private wipers past the last busy trunk line. However, as soonas the private magnet is deenergized the side i a p switch is trippedinto third position; but.

if there are no busy contacts to be passed over, as assumed in thefirstinstance, the 43 .trips the side switch to v tact points.

trunk through the rotary magnet,,57. This cir-' being energized, theshaft wipers 35, 36 and 37 are carried selector leads ofi from the firstset of con-- to the battery lea third position, with the result that theside switch wipers engage their respective con- 38 and 39wpass to third7 osition the subscribers lineconductors 2 and 28 are extended to theconductors leading to the selector switch D; also, since the side switchwiper 40 engages a grounded contact point 56, a guarding potential isestablished at the private wiper 37 for protecting the seized line frombeing molested by any other switch. It will be noticed that after theside switch passes to third position the relay tooth 25' disen ages fromthe spring 19, the

63deenergizes, and the springs 32 and 142 engage with the spring 143,but the engagement of the said. springs at this particular time iswithout efiect, since the side switch wiper 42 has passed to thirdposition'and engaged the idle contact point 58; Furthermore, when theshaft 34 is given the first rotary ste the cam 66 passes out ofengagement wit springs 62 and 63 to disengage. This 'disengagementbreaks the, energizing circuit formed by therotary line relay throughtheprivate magnet 43 and leaves the control of the latter to the guardingpotential (when the side switch wiper 4O isin second osition) on theprivate bank contacts w ich areengaged by the private wiper 37. Thesecond di it is called after the subscriber has established connectionwith the selector D7by way of the trunk conductors 146 and 14 Y 'Whenthe are seized an energizing circuit is established through the verticaland rotary line relays- 89 and 90 of the selector D, in the same mannerin which the circuit was established through the vertical and rotaryline relays of the selector C. The rotary line relay energizing circuitthrough the release relay 95. The circuitthrough the release relayextends from ground G through the springs 91 and93, through the rela. 95to thebatterylead 139, thence through attery B and. to ground G. Therelay, 9'5 energizes and locks the springs 99 and-102 in contact, asexplained. The subscriber rotates thev dial, as described, for thesecond digit 2, thereby shuntingo'r short-circuiting the resistance-coil29 when the sprin 18 and 26 engage. The vertical line re 9g! 89 nowoperatively energizes and places e springs trunk conductors146 and 147When the side switch wipers the spring 63 and. permits-the.

90 energizes and closes an 91 and 92 in contact, whereby a circuit 18'closed through the vertical magnet 75, said circuit/extending from and Gthrough the springs 91 and 92 t tough the magn et.

d 139, ones through battery B and to ground that the vertical magnet 'isenerfgized operates to raise the s aft one step at a. time until thesaid wipers are carried two steps and brought opposite- G. Each time 3and sha wipers the level in which are located the terminals of the-trunkconductors 151 and 152 leading to the connector switch E. In the man- Iner described in connection with the selector C when the switch shaft 84of the selector D moves up the first step, the cam 98 presses the camsprings 96 and 97 into contact, whereby an energizing circuit is set tosecond position,

up through the private magnet 78. This energizing circuit extends fromground G through the line relay springs 91 and 93,

through the cam springs 96 and 97 to the private magnet 78, thence tothe batterylead-139, and through battery B to groundv G. When the rotaryimpulse tooth separates the springs 19 and 30 the energizing circuitthrough the rotary line relay is interrupted, and the said relayrestores the springs 91 and 93 to normal position, which breaks theenergizing circuit through the private magnet 78 and the release relay95. The rivate magnet, upon deenergizing, permits the side switch topass from first being slow-acting, however, the rotary impulse tooth 25disengages from the spring 19, and the energizing circuit of the rotaryline relay is again established, and the' s rin 93 and 91 again engage,closing the ci rcuigz through the release relay before the armature ofsaid relay has time to fall back. When the side switch wiper 81 engagesthe, grounded contact point 148 an energizing circuit is establishedthroughthe rotary magnet '76. This circuit extends from the groundedcontact point 148 A through the side switch wiper 81, interruptersprings 88, rotary magnet 76 to the battery lead 139, thence throughbattery B to ground G. The rotary magnet, by intermittent 'energization,operates to rotatethe. shaft and shaft wipers step' by step and carrythe wipers past the last busy trunk line, if any such are found, asdescribed in connection with selector 0. When the wiper the side switchpasses to third position, thus extending the subscribers line'conductors27 and 28 to the conductors 151 and 152 which lead to the connectorswitch E. Also,

- since the side switch wiper 82 engages the grounded contact point 153,a guarding potential is established at the privatewiper 87 forprotecting the seizedtrunk line from Z being molested by any otherswitch. Of

course, when the side switch passes to third position and the energizingcircuit is broken through the line relays 89 and, 90, the @1 91- Therelease relay 95 gizing circuit is, as a result, also broken through therelease relay 95, which relay then permits the springs 102, 99 and 101to come into contact. The coming into contact of these springs whenthe'side switch is in third the si e switch wiper 83 maintains therelease circuit open at the time. Since the subscribers line conductors27 and 28 are now extended to the connector E, a circuit is establishedthrou h the vertical line relay 108, resistance re ay 29 at thesubstation A, rotary line relay 109 of the connector E. It will benoticed that in each instance when the subscribers vertical and rotaryline conductors 27 and 28 are extended to the next switch a newenergizing circuit is established through the line relays of the newswitch and through the substation re-- sistance coil 29. At the sametime, of course, the old energizing circuit through the line relays ofthe preceding switch is broken. The subscriber ing rela'I 113. Thiscircuit extends from ground through the springs 154 and 155, through thewinding of the relay 113 to the battery lead 139, thence through batteryI rent for energizingjthe vertical linerelay flows from 'ground throughthe rotary line ,relay 1091 0 the'trunk'conductor 152,

shaft wiperj86,'side switch Wiper 80,-conductor 147 shaft wiper:36,rotary conductor 28, springs 26vand 18 to thevertical line con,- ductor27, side switch wiper 38, shaft wip7er 35, conductor 146, sideswitchjwiper shaft wiper'85; conductor 151w the vertical line relay 108,thence to the battery lead 139, and through battery B to ground G Eachtime that the vertical line. relay is energized the line relay springs156 and 154 are pressed into contact, thereby closing an energizingcircuit through the vertical magnet also, the spring 157 is pressed intocontact'with the ground spring 154, where-I by the energizing circuit isestablished through the private magnet 114, The circuit through thevertical magnet extends from ground G through the springs 154 and 156,side switch wiper 117, through the vertical magnet 110 to the batterylead 139, thence through battery B and to ground a G. Each time that thevertical magnet is energized itoperates to raise 'the shaft and shaftwipers one step at a time until the osltion is of no consequence, sincesconductors'27 and, 28 having been extended to the connector E thevvrotary line relay 109 operates and places the springs 154 and 155 incontact, which closes a circuit through the releassaid wipers. arecarried up two steps and brought opposite the level in which are locatedthe terminal contacts of the line #2220. The circuit through the privatemagnet 114 extends from ground G through the springs 154 and 157 to theside switch wiper 118, through the private magnet 114 to the batterylead 139 thence through battery B and to ground The private magnet, uponenergizing, closes the springs 158 and 159 in contact, thereby closing acircuit which locks the private mag-' net in'an operated position. Thislocking circuit extends from ground G throu h the springs 154 and 155,'springs 158 an 159, through the winding of the private ma net 114 tothe batter lead 139, and throug battery B to ground G. When the rotaryline relay 109 deenergizes, due to the rotary impulse, the lockingcircuit through the private magnet 114 is broken. The private magnet'nowdeenergizes and permits the i side switch to pass to second position,thus I placingthe side switch wipers 115, 116, 117,

118'and 119gin connection with their respectivecontact points in secondposition. Dur- 0 nauIgjht' the, subscriber energizes the vertiing the'time in which the rotary-relay 109 is deenergized the releasing relay113 is maintained in its operated position b the residual magnetism. Thelast digit eing cal ne relay-108 ten times and deenergizes 'therojtaryline relay 109 once. However,

' whenfthe line relay springs 156and 154 engage, a circuit is therebyclosed through the rotary magnet-111 instead of through the verticalmagnet 110. The energizing circuitextends from ground G through thesprings 154 and 156, side switchwiper 117' 40: p

' tery lead 139, and through. battery B to .to the rotary magnet 111,thence to the batground G. Each. time that the rotary magnet isenergized it rotates the shaftan'd shaft wipers 105, 106 and 107 one steat a time until 7 the said wipers are carrie into engagement with thenormal conductors 160', 161 and 162, the first two of which lead to theline terminals of the desired subscriber. Also, when the vertical linerelay 108 energizes, the spring 157 is pressed into contact with thesprin 154, thus again closing an energizing circuit through the privatemagnet 114 which again operates and locks itself in an operatedposition] The deenergiza tion of the rotary line relay 109, when therotary impulse tooth 25 separates the springs 19 and 30, causes thelocking circuit of'tho private magnet 114 to be again interrupted. Theprivate magnet deenergizes, and one of two results occurs, namely therelease of the side switch from second to third position, or theso-called busy-release of the connector, which will'bedisclosedhereinafter. Suppose the former rebridgln wipers 115, 116, 117,113 and119 in contact with their respective contact points in third position.Tl1en,when the side switch passes to third position a guarding potentialis established for protecting the called line. This potential extendsfrom ground Gr through the side switch wiper 119 to the shaft wiper 107which engages theprivate contact of the called line. The said guardingpotential also closes an energizing circuit through the cut-off relay163 of the first-selector C, thereby removing the bridge formed by therotary and vertical line relays 114 and 115 of the selector C. Theenergizing circuit for the relay 163 may be traced from ground G to theprivate wiper 107, thence through the private normal conductor 162switch shaft springs 116' and-117" to the bridge-cut-ofi relay 163,thence to the battery lead 139 and through battery B to ground G. Ofcourse, when the relay 163 energizes it separates the springs 118 and119 from the springs 120* and 121", thereby disconnecting the relayssubscriber presses the signaling button 31, whereby the spring 32 isplaced in contact with the contact point 33, as a result placing indirect connection the vertical and rotary line conductors 27 and 28.This now causes an increase of current-flow throughv t the connectorvertical line relay 108. will be remembered that the connector sideswitch has-passed from second to third .po-

- springs 154 and 156 into contact the ringer relay 112 is energized bya flow of current from ground G through the springs 154 and 156, sideswitch wiper 117, contact point 164, ringer relay 112 to the bat lead139,

and from battery B to groun -G. The ringer relay, upon energlzing,shifts the springs 165 and 166 out of contact with the springs 167 and168 and into engagement with the springs 169 and 170.' This results inseparating the callin subscribers line from the called subscri rs line,and in g across the line of the latter the terminals of the ringergenerator H. The signaling current is therefore, sent from the ri rgenerator H to the ringergenerator .114and 115 from the batteryterminals. To signal the calledsubscriber, the calling sprmgs 169 and165, side switch 115, shaft I wiper 105, normal conductor 160, verticalconductor 171, condenser 172, ringer 173,

, 188 in contact, whereby a series circuit is switch hook 180, therebyremovin 174 and 175, rotary impulse springs I sp s 1 6 and 177 to therotary lme conductor- 178, normal conductor 161, shaft wiper .106, sideswitch wiper 116, ringer relay springs 166 and 170, back to thegenerator H. soon as the calling subscriber ceases to press thesignaling button 31 of the ringer relayv 112 becomes deenergized, andthe springs 165 and 166 resume their normal position in contact with thesprings 167 and 168. The subscriber A, in response to the signal,removes the receiver 179 from tfie t 'e ringer 173 from across his lineand bri ging, instead, the secondary circuit which includes the receiver179, the secondary winding 181 of the induction coil 182, secondarysprings 183 and 175 and rotary impulse rin 176 and 17 7 The localtransmitter circuit is closed as soon as the springs 185 and 186 engagein contact. The two substations #5000 and #2220 are now connected overthe circuit shown by heavy lines in Figs. 1 and 2.

The release of the central office apparatus 3 occurs when the callingsubscriber restores the receiver 2 to the switch hook 3, therebybreaking the connection between the springs 6 and 7 at the substation,whereby the energizingcircuit through the rotary line relay 109 of theconnector E is broken-that is,

the line conductors 27 and 28 are disconnected. The rotary line relay109 of the connector E, upondeenergization, permits the sprin 154 and155 to disengage, thereby breakmg the circuit through the releasingrelay 113. The releasing'relay 113in turn .deenerfiizes and places thelocked springs i 131 an "40 129' in contact with the spring 130, therebyclosing an energizing circuit through the'release relay 121. Thiscircuit extends from ground Gr through the relay 121, springs 131, 129and 130 to the-'batte lead 139, andthr'ou'gh battery B to ground As therelay armature 133 returns to normal 0- sition the latch 132 slides uponthe beve ed member 134 and unlocks the springs 131 and 129, aspreviously explained. The rela 121, upon energizing, closes the springs18 and closed through the release relay 94 of the selector D and releasemagnet 120 of the connector '13. This circuit extends from ground G atthe selector D to the contact point 153, side switch wiper 82, releasereay 94, conductor 149, private'shaft'wiper 87 ,conductor 189, throughthe springs 187 and 188, releasemagnet 120 tot e battery lead 139, andthrough battery B to ground G. The release niagnet 120, being thussuplied with current, energizes and o crates 3 1n the well-known mannerto restoret e corrnector shaft and shaft wipers to their normalposition. The release relay. 94 of the selector D -also energizes andplaces the vcircuit extends from springs 190 and 191 in contact, whereby0. clrcuit is completed through the release magnet 77 of the selector Din series with the release relay 65 of the first-selector C. This ound Gat the selector C through the si e switch Wiper 40, release relay 65,private wiper 37 release relay springs 191 and 190, through the windingof the release magnet 77 to the battery lead 139, and through battery Bt0 7 ground G. The release magnet 77 in turn operates to release thesecond-selector D. Also, when the armature is attracted, the s end 103pressesthe latch 100 out of engagement with the spring 102,thus allowingthe 80 locked springs 102 and 101 to disengage and return to normalposition. The release relay 65 of the selector C also energizes andplaces the springs 192 and 193 incontact, whereby 'an energizing circuitis closed through the release magnet 64 at the selector 0. This circuitextends from ground through the springs 193 and 192 to the relay 64, tothe battery lead 139, and through battery B to ound G. The releasemagnet 64 operates to press the latch 31 out of engagement with thespring 32, and to restore the first-selector shaft 34 to normalposition.

The busy release of the connector E follows as a result of thedeenergization of the rotary line relay 109, if the called line is busy.If, when the private magnet 114 deenergizes for the last digit, thecalled line is busy a ground impulse is transmitted from the shaft wiper107 to the side switch 1 wiper 119, contact point 194 through thesprings195 and 196 to the release magnet 120, thence to the battery lead139, and through battery B to ground G. The re-' lease magnet, uponenergizing, releases the 1 connector switch shaft and restores the con--nector side switch to its first position, returning the vertical magnetto the control of the vertical line relay 108; therefore, if the callingsubscriber (Fig. 1) now presses 110 the signaling buttonv 31 andenergizes the vertical line relay 108, the latter -now operates thevertical magnet 110. .The vertical magnet in turn so raises theswitch-shaft that the normal post 126 permits the switch shaft sprin 127to engage the contact point 128, and a usy signaling current is sent tothe calling subscribers station. The calling subscriber, upon hearingthe busy-signal, will understand that the desired line is in service,and will release the switching a paratus over the same-circuits previousy described. The functions of the relay 63 of the selector C and therelay 95 of the selector D are to release before the side switch 3 haspassed to third osition. u pose that in making a call t e selector O asbeen operated and established connection with the selector D, andthat-it is desired to release the selector 0 and make a new call. In

that event, when the subscriber restores the receiver 2 to theswitch-hook 3 and separates the line conductors 27 and 28, theenergizing circuit through the rotary relay 90 is then broken, and thesprings 91 and 93 separate, whereby the circuit through the releaserelay 95 also becomes broken. The springs 102 and 99, which are lockedin con tact, now engage the spring 101, whereby an energizing circuit iscompleted through the release magnet 77 of the selector D in series withthe release relay of the selector C. Thiscircuit extends from ground Gthrough the release relay 65, shaft wiper 37, through the springs 102,99 and 101, side switch 83, contact point 197 to the release magnet 77,thence to the battery lead 139, and through battery B to ground G. Therelease magnet operates, as before, to release the selector; D, and therelease relay 65 energizes and closes a circuit through the releasemagnet 64, as above. Similarly, the selector C may be released while theside switch is in first or second position by thebreaking of theenergizing circuit through the rotary line relay 61, thus permitting thesprings 140 and 141 to disengage, whereby the circuit through theprivate magnet 43 and release relay 63 is also broken. The

locked springs 14-2 and 32' engage the spring 143, thus closing acircuit through the re-' lease magnet 64.; This circuit extends fromground G through the springs '32, 142 and 143, side switch'wiper 42,contact point 53 to the release magnet 64, thence to the battery lead139, and through battery B to ground G.

The relay 63 may be wound toany suitable resistance, but good resultshave been obtained when said relay is wound to a resistance oftwenty-three hundred ohms; the release relay 95 may be wound to. aresistance of twenty-three hundred ohms; the

vertical line relays 59, 89 and 108 to five hundred ohms; the rotaryline relays 61, 90 and 109 to five hundred ohms; and the substationresistance coil 29 to three thousand ohms.

From the foregoing it will be seen that by my invention I provideimproved means for controlling a. plurality or series of automaticstep-by-step switches without employing operating grounds at thesubstations.

In other words, I employ a series of switches for trunking a callingsubscriber into con-' nection with a called subscribers line, and do soby improved means comprising line circuitsincluding both sides of theline in series, no grounds being necessary outside of the centralstation or exchange for controlling the trunking switches andconnectors. In this way the subscribers telephone lines are free fromoperating grounds outside of the exchange or central station,

and all line circuits employed for controlling, theexchange apparatusare of an en- 4 tirely metallic character and do not include the ground.The advantages accruing from the use of nongrounded telephone lines andsubstations are many, and will be obvious to those skilled in the art.

. \Vhat I claim as m invention is:

1. A telephone exc ange system co'mprising a telephone line, anautomatic switch provided with a switch shaft supported for both endwiseand rotary motion, means for closing the two sides of the line togetherto move the shaft endwise, means including a I line relay responsive tosuch closing of the ing a telephone line, an automatic switch providedwith a bank of contacts arranged in a plurality of levels, a rotaryswitch. shaft adapted to be raised'to any one of said levels, asubscribers device for closing together the-two sides of the line, meansincluding aline relayresponsive to the clos ing of the line for raisingthe switch shaft,

adapted to step the latter up to any level, according to the number oftimes the line is closed, means for automatically rotating the shaft atany level to find an idle contact therein, means for cutting oil thelinerelay while the shaft is in its rotated position,

and 'means for restoring the switch shaft to normal position by theopening' of the line;

3. A telephone exchange system comprising a subscribers telephone line,an auto-- matic switch provided with .a rotary and endwise movableswitch shaft, a line relay for controlling the endwise movements of saidshaft, means including another line relay for controlling the rotationof the shaft, line circuits for energizing said relays,

and means for cutting off said relays while the shaft is in its rotatedposition, each line circuit including the two sides of the tele.-. phoneline in series.

-4..A telephone exchange system compriss ing a subscribers telephoneline including a pair of talking con uctors, an automatic switch, arotatable calling device adapted by its backward rotation tointermittently close together the two talkingconductors'of the telephoneline, a line relay in said switch for responding to the intermittent,closing of the line, means for thereafter cutting off said relay, andmeans for "restoring the switch to normal position by. opening the line.r.

5. A telephone. exchangeisystem comprisinga calling telephone line, acalled teles phone line, a progressively movableselector talking circuitand extendin from the selector to the connector, and a t ird or trunkrelease relay for controlling said release circuit.

6. A telephone exchange system comprising a calling telephone line, acalled tele phone line, trunk lines including a pair of talkingconductors and a separate release conductor, automatic switches foruniting said trunk lines to establish a connection between saidtelephone lines, means for. signaling the called subscriber by closingtogether the two sides of the calling line after the said telephonelines are connected together,

apparatus for releasing said switches, and a,

circuit including said release conductor and extending from one switchto another for operating said apparatus.

7 Atelephone exchange system compris ing telephone lines each includinga pair of talking conductors, automatic connectors less in number thansaid telephone lines, selectors less in number than the telephone lines,subscribers individual switches corresponding in number tothe telephonelines, subscribers devices for closing together the two sides of thelines to. control said individual switches and selectors and connectors,line circuits by, which the said individual switches and selectors andconnectors are controlled to establish a talking circuit between two ofsaid telephone lines, each line circuit including said pair of talkingconductors of a calling telephone line in series, and means includingrelease trunks separate from the talking circuit and extendingrespectively from said individualswitches to said selectors and fromsaid selectors to said connectors for restorin said individual switchesand selectors an connectors by the opening of the callin lines.

8. A telephone exc iange system comprising a second selector, a pair oftalking conductors extending thereto, and a battery having one polegrounded, said selector provided with a vertical line relay permanentlyconnected to nongrounded battery, with a rotary line relay permanentlgrounded battery, said re ays normally bridged across said talkingconductors, and

with means for disconnecting said relays from said talking conductors.

9. A telephone exchange system compris-- ing a pair oftalking conductorsand a connected to rotary line relay normally connected to one of saidconductors, anenergizing circuit for said relay, means for disconnectingsaid relay from said conductor, means for causing short interruptions 1nthe energizing circuit of said relay, and a slow acting relay adapted toenergize when the said line relay is ener ized, and adapted to remainenergize durin the short interruptions in the energizin circuit of thesaid line relay.

10. A telephone exchange system comprising a selector provided with aside switch, a trunk line including a pair of talking conductors leadingto said selector, a circuit including said talking conductors in seriesfor controlling the operation of said selector, a

release-relay for releasing said selector while the side switch is infirst or second position, and a release relay for releasing the saidselector when the side switch is in third position. I a

11. A telephone exchange system com rising a release relay provided witht iree springs, and a catch on one of said springs adapted to lock theother two of said springs together when the release relay energizes, aside switch wiper connected with one of the springs, a trunk releaseconductor, a selector having a private wiper, said trunkreleaseconductor connecting another of said springs withvsaid privatewiper, said catch causing the locked pair of springs to be brought intoelectrical connection with the third spring when the release relaydeenergizes to place the side switch wiper in electrical connection withthe said trunk release conductor.

12. A telephone exchange system wherein the subscribers lines eachinclude a pair of talking conductors and wherein the central ofiiceapparatus is controlled over circuits including the said talkingconductors in the side switch of the seconll selector is in u first orsecond position.

13. A telephone exchange system comprising a selector providedwith aside switch,

a release relay provided with a pair of springs, means for locking saidsprings to,- gether, a release 1nagnet. a rotary line relay, a. switchshaft adapted to be raised step by step, a pair of springs adapted to beoperated by said shaft, an armature for said release magnet, saidarmature ada ted to unlock the release relay springs wien the releasemagnet energizes, and a private magnet ,only while the said side switchis in first position.

14. A telephone exchange system wherein a pair of talking conductorslead to an automatic switch, a switch shaft, a rotary line relaynormally connected to one of said talking conductors, means fordisconnecting said relay from said talking con- ,ixluctor, a privatemagnet, and an energizing circuit for said private magnet controlled bysaid switch shaft and rotary line relay, said shaft provided with meansfor raising and rotating it, means operated by said shaft and relay forsetting up the said circuit while the rotary line relay is energized andthe switch shaft out of normal vertical position but in normal rotaryposition, said energizing circuit when established adapted to be brokeneither by the rotation of-the shaft, by the deenergizing of the rotaryline relay, or by both.

15. A telephone exchange system comprising a first selector, asecond.selector provided with a side switch,-a trunk line including a air oftalking conductors leading to said second selector, arotary line relaynormally connected to one of said talking conductors, means fordisconnecting said-relay from said talking conductor, and means forenergizing said relay after the first selector extends connection to thesecond selector adapted to maintain the relay energized as long as theside switch of the second selectorren'iains v in first or secondposition.

16. A telephone exchange system comprising a second selector providedwith a vertical side switch wiper, a vertical line relay,- a verticalline wiper, a trunk conductor adapted to be switched by 'the switchwiper from the vertical line relay to the vertical line wiper, a rotaryside switch wiper, a rotary line relay, a rotary line wiper, a rotarytrunk conductor adapted to be switched by the rotary side switch wiperfrom the rotary line relay tothe rotary line wiper, a,rotary magnet,aside switch wiper for closing circuit through the rotary magnet whilethe sideswitch is in second position, a private magnet, a side switchwiper adapted to close circuit through the private magnet to lock theside switch in second position and to maintain circuit through therotary mag- 'net, a private wiper, bank contacts adapted to be engagedbv said private wiper, said energizing circuit maintained through therotary magnet adapted to be opened as soon as the private wiper passesout of engagement with busy bank contacts, a release magnet, a releaserelay spring, and a side switch wiper for maintaining the reing saidmagnet.

lease magnet in connection with the said release relay spring while thesaid switch is in first or second position, adapted for breaking suchconnection between the release magnet and the release relay spring whenthe side switch passes to third position. V

17 .A telephone system comprising a sec-. ond selector provided with aprivate magnet, a switch shaft and springs controlled thereby, arotaryline relay, a back rtlease relay, a private wiper, and asideswitch provided with a SWItClI wiper, said private magnet having aplurality of energizing circuits whereof one 'is controlled by the shaftcontrolled springs and the rotary line relay, another of said circuitsbeing controlled by the private magnet itself and including said switchwiper and back-release relay and theprivate wiper.-

18. A telephone system comprising a battery having one pole grounded, aconnector provided with a rotary line relay having one terminal thereofpermanently connected to ground, a vertical line relay hav-. ing oneterminal thereof ermanently connected to the non-grounded terminal of.the battery. a trunk line including a pair of talking conductors and aseparate conductor leading to said, connector, a selector forestablishing connection with said three conductors, a magnet forreleasing said connector, and a circuit including said separateconductor and extending from sald selector to sa d connector for operat-'19. A telephone system comprising a s ec- 0nd selector, a connector, atrunk line including a pair of talking conductors and aseparate-conductor leading to said connector, a line relay forcontrolling the operation of said connector to extend a connecing saidconnector, and a circuit including said separate conductor extendingfrom said selector to said connector for operating said magnet.

'20. A telephone system wherein the trunk V lines extending betweehtheautomatic switches each include a pair of talking con-.. ductors and aseparate conductor, fa rotary line relay, a pair of line conductors, asubstation high resistance coil, a vertical line, relay, a. circuit forenergizing said rotary line relay, said circuit including said lineconductors, said resistance coil, and said vertical line relay, theresistance of said circuit being adjusted to permit the operation of therotary line relay and prevent the operation of the vertical line relay,means for short circuiting or shunting the resistance coil to lay, arotary gizing circuit rotary line relay,

three conductors; a slow-acting release re-.

lay adapted to energize when the said rotary line relay is energized, amagnet for releasing said connector, and a circuit including said searate conductor and extending from said se ector to said connector foroperating said magnet.

22. An automatic telephone exchange system comprising a connectorprovided with a a slow-acting relay, an energizing circuit said slowacting relay being provided with springs, and means for locking saidsprings together when the slow acting relay is ener-' gizing, said slowacting relay adapted to remain energized during short interruptions ofthe energizing of the said rotary line relay.

'23. An automatic telephone exchange system comprising a connector andmeans for seizing said connector, the said connector being provided witha slow acting relay adapted to remain energized from the time theconnector is seized until the calling subscriber releases, a rotary linerelay, means for deenergizing said rotary line relay when the callingsubscriber releases, means by which the deenergizing of said rotar. linerelay causes the deenergizing of 'sai slow acting relay, a releasemagnet, a beveled sto thr de springs and with a latch for momentarilyuniting said springs in electrical contact, said latch adapted to strikesaid stop when said slow acting relay is deenergized, a

release magnet and an energizing circuit I therefor adapted to be openedby the separation of two of said springs, substantially as set forth.

24. A, telephone exchange system comprising a private magnet, a verticalline reline relay, and a locking enerfor the private magnet adapted tobe set up by the vertical line relay and adapted to be broken down bythe rotary line relay.

241A telephone exchange system comprising a vertical line relay, arotary line relay,

a side switch, and a locking energizing circuit adaptedto be set up bythe vertical line relay while the side switch is in first or secondpositionand adapted to be broken by the rotary line relay. I

26. A telephone system comprising a private magnet, a side switch andprivate wiper,

for the slow acting relay,

the private said slow acting relay provided witha rotary line relay andarelease magnet, a circuit for initially energizing said private magnet,a locking circuit for said private magnet controlled by said rotary linerelay, a couple of energizing circuits for said re lease magnet, one ofwhich circuits is controlled by the private ma et adapted to be set upwhile the side switch is in second position and the private wiper on agrounded contact point at the instant that the rotary line relay breaksthe locking circuit of the prlvate magnet.

27. A telephone system comprising a vertical line relay, a sideswitch,'a rotary magnet controlled by the vertical line relay while theside switch is in second position, a shaft and shaft wipers rotatedtherebyin a step by step manner, a private wiper, a release magnet, anenergizing circuit therefor, established while the side switch is insecond position, comprising private magnet springs,

private wiper stops upon a d grounded contact point, an

a locking energizing circuit for magnet adapted to be established by thevertical line relay upon its first operation, after the side switchpasses to second position, in order to maintain the said private springsseparated, and to prevent the establishment of the said release magnetenergizing circuit while the private wiper is bein rotated. I

28. A telep one system comprising a con- 'nector side switch, verticalandrotaryline relays 'for operating said side switch, and a privatemagnet, said side switch controlled by the private magnet and adapted toshift from first to second position and from second to third position,the shift from first to second position produced by the vertical linerelay. energizing the 'rivate magnet and locking the latter, and by therotary line relay subsequently breaking down the said locking circuit,-the shift from second to third position produced by'the vertical linerelay again energizing and locking the private magnet, and by the rotaline relay subsequently breaking down the ocking circuit.

29. A tele hone system comprising a vertical line re ay, a verticalmagnet, and a private magnet combined to energize to.- gether.

30. A telephone system comprising a selector, a side switch therefor,another selector for extending connection to said first mentionedselector, a rotary line relay for said first mentioned selector adaptedto energize as soon as the first mentioned selector is seized, a slowacting release relay energized thereby, said slow acting release relayremaining in readiness to release said selectors if the subscribershould desire to do so before said side switch passes to third position.

' release circuits for the selectors controlled by the connectors,telephone lines, and line circuits for successively controlling one ormore of said trunk-selectors and a connector to extend connection to acalled telephone line, each circuit including the two sides of a callingtelephone line inseries, and means for releasing the selectors andconnectors by the opening of a connected telephone line.

32. A telephone system comprising trunkselectors, line relays for saidselectors, op erating circuits controlled by said relays, means forcutting off said line relays, automatic connectors, line relays for saidconnectors, circuits controlled by said last-mentioned relays forcontrolling the operation thereof to extend connection therefrom, asource of operating current, said source of current normally bridged'between the relays of the connectors, metallic line circuits forcontrolling the said relays, and trunk release circuits for theselectorscontrolled by the connectors.

33. A telephone exchange system comprising telephone lines eachincluding a pair of talking conductors, automatic connectors less innumber than said telephone lines, provided with means having verticalmotion from one operative level to another to select groups or divisionsofthe exchange, and rotary motion in any selected level to connect witha line therein, selectors less in number than the telephone lines,subscribers individual switches corresponding in number to the telephonelines, subscribersdevices for closing together the two sides of thelines to control said individual switchesand selectors and connectors,line circuits by which the said individual switches and selectors andconnectors are controlled to establish a talk ing circuit between two 0fsaid telephone lines, each line circuit including said pair of talkingconductors of a calling telephone line in series, and means includingrelease trunks separate from the talking circuit and extendingrespectively from said individual switches to said selectors and fromsaid selectors to said connectors for restorin said individual switchesand selectors an connectors by the opening of the calling line.

34. A telephone exchangesystem comprising a second-selector, a pair oftalking conductors extending thereto, and a battery having one polegrounded, said selector pro-u vided with means having vertical motionfrom one operative level to another to select groups or divisions of theexchange, and rotary motion in any selected level to connect with a linetherein, and provided also with a vertical line rela permanently connected to nongrounded battery, with. a rotar line relay permanentlyconnected to grounded battery, said relays normally bridged across saidtalking conductors, and

means for disconnecting said relays from said talking conductors.

35. A telephone exchange system comprising a selector provided withmeans'hav- 111g vertical motion from one level to another to selectgroups or divisions of the I exchange, and rotary motion in any selectedlevel to connect with a line therein, and provided also with a sideswitch, a' trunk line" includin a pair of talking conductors leading tosald selector, a circuit including the said talking conductors in seriesfor controlling the operat-ion of said selector, :1

"release relay for releasing said selector while I the side switch is infirst or second position, and a release relay for releasing the saidselector when the side position.

36. A telephone exchange system comprising a selector provided withmeans having vertical motion from one operative level to another toselect groups or divisions of the exchange and rotary motion in anyselected level to connect with a line thereinand provided also witha'side switch, a release relay provided with a pair of springs, meansfor locking said springs together, a release magnet, a rotary linerelay, a switch shaft adapted to raised step by step, a pair of springsadapted to be operated by said shaft, an armature for 'said releasemagnet said armature adapted groups or divisions of the exchange androtary motion in any selected level to connect with a line therein, andprovided also with a side switch, a trunk line including a pair oftalking conductors leading to saidv 1y connected to one of said talkingconductors, means for disconnecting said relay from said talkingconductor, and means for energizing said relay after the first selectorswitch .is in third 1 second selector, a rotary line relay normalextendsconnection to the second. selector adapted to maintain the relayenergized as long as the side switch of the second selector remains infirst or second position.

38. A telephone system comprising a battery having one pole grounde aconnector provided with means having vertlcal motion from one level toanother to select groups or divisions of the exchange, and rotary motionin any selected level to connect with nection with said threeconductors, a magnet for releasing said connector, and a 011' cuitincluding said separate conductor and extending from said selector tosaid connector for operating said magnet.

39. A telephone system comprising a second' selector, a connectorprovided with means having vertical motion from one level to another toselect groups ordivisions of the exchange and rotary motion in anyselected level to connect with a line therein, a trunk line including apair of talking conductors and a separate conductor leading to saidconnector, a line relay for controlling the operation of said connectorto extend a connection therefrom, a circuit including said pair oftalking conductors-in series for energizing said line relay, means forclosing said circuit as soon as the selector seizes said trunk line, amagnet for releasin said connector, and a circuit including saidseparate conductor and extending from said selector to said connectorfor operating said magnet.

40. An automatic telephone exchange system comprising a connectorprovided with means having vertical motion from one operative level toanother to select groups or divisions of the exchange, and rotary motionin any selected level to connect with a line therein, and provided alsowith a rotary line relay, a trunk line including a. pair of talkingconductors and a separate conductor leading to said connector, aselector for establishing connection with said three conductors, aslow-acting release relay adapted to energize when the said rotary linerelay is' energized, a magnet for releasin said connector, and a circuitincluding said separate conductor and extending from said selector tosaid connector for operating said magnet. p

41. An automatic telephone exchange system comprising a connectorprovided with means having vertical motion. from one operative level toanother to select groups or divisions of the exchange, and rotary motionin any selected level to connect with a line therein, and provided alsowith a rotary line relay, a slow-acting relay, an energlzmg circuit forthe slow-acting relay, said slowfacting rela being provided with a pairmeans for locking said springs together when the slow-acting relay ed toremain energized during short interruptions of the energizing of thesaid rotary line relay.

42. An automatic telephone exchange system comprising a connector, meansfor seizing said connector, the said'connector being provided with meanshaving vertical motion from one operative level to another to selectgroups or divisions of theexchange, and rotary motion in any selectedlevel to connect with a line therein, and also pro vided withajslow-acting relay adapted to remain energized from the time theconnector is seized until the calling subscriber releases, a rotary linerelay, means for deenergizing said rotaryline relay when the cal]- ingsubscriber releases, means by which the deenergizing of said rotary linerelay causes the deenergizingof saidslow-acting relay, a release magnetand a beveled stop, said slow-acting relay provided with three springsand with a latch for momentarily uniting said springs in electricalcontact, said latchadapted to strike said stop when said slow-actingrelay is deenergized, a release magnet and an energizing circuittherefor adapted to be opened by the separation of two of said springs.I

43. A telephone system comprising automatic trunk-selectors, automaticconnectors provided with means having vertical motion from one level tovanother to select groups or divisions of the exchange, and rotary motionin any selected level to connect with a line therein, trunk lines eachincluding a pair of talking'conductors leading to said connectors,trunk-release circuits for the selectors controlled by the connectors, avariablyrotative calling dial at each substation, a source of operatingcurrent, said 1 provided with a bank of contacts arranged in a pluralityof levels, and with a rotary switch shaft-adapted to be raised to anyone of said levels in accordance with a. digit of the called number, asubscribers device for closing together the-two sides of the line,

adapted to come to rest before actuation thereof to transmit impulsesfor the next digit, means including a line relay responsive to theclosing of the line for raising the switch shaft, adapted to step thelatter up to any level, according to the number of times the line isclosed, means for automatically rotating the shaft at any level .to findan idle contact therein, means for cutting off the line relay while thshaft is in its rotated position, and 'meansfor restoring the switchshaft .to normal positionvby the opening of theline. i

45. In a telephone exchange trunking sys-.

tem, a subscribers telephoneline, an autos maticswitch provided with arotary and endwise-movable switch shaft. a line relay for controllingtheendwise movementsnof said shaft, means including another linerela'y'for controlling the rotation of the shaft,

line" circuits for energizing said relays, means for cutting off saidrelays while the shaft is in its rotated positiom'each line circuitincluding the two sides of the telephone line in series, and a callingmechanism for controlling said circuits, adapted to come to rest uponthe completion of the endwise motion of said shaft.

v 46. In a telephone exchange trunking system, asubsc'ribers-telephoneline, an auto- 'matic switch provided with a rotary and endwise-movableswitch shaft, another automatic switch, a trunk line including a pair oftalking conductors and a separate conductor leading from said firstswitchto said other switch, means including a line circuit forcontrolling the rotation of the shaft to seize said trunk line, eachlinecircuit including the two sides of the'telephone line and said pair oftalking conductors all inserics, means for controlling said circuitsadaptal to return to normal upon the completion of the endwise movementofsaid shaft, release mechanism forsaid first switch, and a circuitincluding said separate conductor and controlled by said other switchfor operat-.

ing said mechanism. a

47; In atelephone exchange trunking system, telephone lines eachincluding a pair of talking conductors, automatic connectors less innumber than, said telephone lines, se-

lectors less in number than theftelephone lines subscribers individualswitches corresponding in number tot-he telephone lines, subscribersdevices for closing together the two sides of the lines to control saidindividual switches and selectors and connectors, each device adapted tocome to rest after one digit and before calling the next digit, lineswitches and selectors and connectors are 'controlled to establish atalking circuit bea tween two of said telephone'lines, each line circuitincluding the two sides of a calling telephone line in series, and meansincluding release trunks separate from the talking circuit and extendingrespectively from said. individual switches to said selectors and fromsaid seledors to said connectors for restoring said individual switchesand selectors andic'onnectors by the opening of the calling line. i f 148. In a telephone trunking system, tru nktrun -releas e circuits forthe selectors controlled by the connectors, and means forcontrollingsaid relays adapted to come to rest after each separateoperationv thereof for each digit of the callednumber.

49. In an automatic telephone exchange system employing bridging linerelays, a

calling telephone line, a calledtelcphone line,-a series of automaticswitches for extending connection from the'calling line to the calledline, having provisions for automatically reducing the number-ofbridgesacross the talking circuit during the =establishmentthereof, threeconductor trunks tweenisaid switches, and a plurality of line: circuitsby which said switches are succes sively controlled, each said: linec-ircuit in cluding the two sides of the calling hne 1n series.

50. In a telephone exchange system employing bridging line relays,,acalling tele-. phone line, :1 called telephone line, means including aplurality of selectors and a connector for extending connection from thecalling line to the calledline, having lprovisions for automaticallyreducing the number of bridges across the talking circuit,

during the establishment thereof, three-0on5" ductor trunks between saidswitches, "line line circuits for controlling the connector,

each line circiut including the two sides of switch shaft, havingprovisions for automaticall reducing the number of bridges across t etalking circuit during the-establishment' thereof, means including aline-circuit for controlling the endwise movements 1 of the switchshaft, means including a line in circuit for controlling the. rotationof the V shaft, and a trunk-release circuit for re- OllCllltS by whichthe sald indivldual storing said switch, each line circuit inin series.v

52, In a telephone system employing bridging line relays, a line, aplurality of electrically-pro elled and step-by-step actuated switchesraving provisions for automatically reduclng the number of bridgeslishment thereof, three-wire connections be i tween saidswitches, linecircuits for suecessively controlling said switches, andfl a'"subscribers device for intermittently clos ing together the two sides ofthe line to 10 circuits for controlling the selectors, and

across the talking circuit during the estab-.-

establish said circuits, each line circuit including the two sides ofthe line in series.

53. In a telephone exchange stem emlploying bridging line relays, telepone lines, automatic connectors less in number than saidtelephone lines,selectors less in numher 'than the telephone lines, having provisionsfor automatically reducing the number of bridges across the talkingcircuit during the establishment thereof, subscribers individualswitches corresponding in number to the telephone lines, subscribersdevices for closing together the two sides of the lines to 'control'said individual switches and selectors and connectors, line circuits bywhich the said individual switches and selectors and connectors arecontrolled, each line circuit including the two sides of a callintelephone line in series, and means inc uding release trunks forrestoring said individual switches and selectors and connectors by theopening of the calling lines.

54. In a telephone system employing bridging line relays, subscribers teephone lines, automatic means for trunking a call ing ,line intoconnection with a called line, having provisions for automaticallyreducing the number of bridges across the talking circuit during theestablishment thereof, including three-wire trunks, and successive linecircuits for controlling said automatlc trunking means, each linecircuit 1ncluding the two sides of the calling telephone line in series.

55. In a telephone system employing bridging line relays, trun selectorshaving provisions for" automatically reducing the number of bridgesacross the talkin circuit during the establishment" thereo line relaysfor controlling said selectors, means for cutting off said line relays,automatic connectors, line relays for said conn tors for controlling theoperation thereof to extend connection therefrom, a source .ofop--eratin current, said source of current normally ridged between therelays of the con-. nectors, and trunk-release cireuits for theselectors controlled by the-connectors.

56. An automatic tele hone exchange system comprising subscri ers lines,a, seriesof automatic switches for-trunking a calling subscribers lineintoconnection with a called subscribers line, a bridge contain-i igg anoperating element and av ridge cut- 0 relay for each subscribers line,trunk lines each including a pair of talking conductors and a separateconductor between said switches, circuits each including a pair of saidtalking conductors in series for operating said switches, meansindependent of the earth at the calling subscribers station forcontrolling said circuits, a magnet for releasing the final one of saidseries of switches, and a circuit including said separate conductor ofone ofsaid trunk lines for'operating said magnet.

out 01f relay for each telephone line, trunk.

lines, each including a pair of talking conductors and a separateconductor between said switches, a plurality of line circuits by whichsaid switches are successively controlled, each said line circuitincluding said pair of talking conductors of the calling hne in series,a magnet for releasing the final one of said series of switches, and acircuit including said separate conductor of one of said trunk lines foroperating said magnet. ,7

58. A telephone exchange system comprising a calling telephone lineincluding a pair of talking conductors, a called telephone line, meansincluding a. plurality of selectors and a connector for extendingconnection from a calling line to a called line, a bridge containing anoperating element and a bridge cut off relay for each telephone line,trunk lines each including a pair of talking conductors and a separateconductor between said switches, a plurality of line circuits forcontrolling each of said selectors, a plurality of line circuits forcontrolling said connector, each of said line circuits including saidpair of talking conductors of the \calling line in series, a magnet forrei a pair of talking conductors and a separate conductor between saidswitches, means for signaling the called subscriber by closing togethersaid pair of talking conductors of the calling line after the two linesare con nected together, a magnet for releasingone of said switches, anda circuit including said separate conductor for operating said magnet. a

60. A telephone exchange system comprisin telephone lines each includinga pair 0 talking conductors, a bridge containiriiig an operating'elementand a bridge out o relay for each telephone line, automatic connectorslessin number than said telephone lines, selectors less in number thanthe telephone lines, subscribers individual switches corresponding innumber to the telephone lines, trunk lines each including a pair oftalking conductorsand a separate conductor, some of said trunk linesextending between said selectors and connectors and other of said trunklines extending between said individual switches and selectors,subscribers devices for closing together said pair of talking conductorsof the telephone lines to control said individual switches and selectorsand connectors, line circuits 'by which said individual switches andselectors and connectors are controlled, each line circuit includingsaid pair of talking conductors of a calling telephone line in series,and means including release circuits for restoring said individualswitches and selectors and connectors by the opening of said pair oftalking conductors of the calling line, each said release circuitincluding said separate conductor of one of said trunk lines.

61. In a telephone systema called telephone line, an automatic switch,a. trunk line including a pair of talking conductors leading thereto,means for making connection to said trunk line, means for controllingsaid pair of talking conductors in series to control said switch toconnect with said called line, said switch having a controlling magnetconnected to one of said talking conductors, and means whereby saidmagnet is disconnected from said talking conductor during the use of thelatter for talking purposes.

62. In a telephone system, a. switch, means I including arelease-magnet. and a release magnet circuit for releasing the same, a

slow-acting relay controlling the release magnet circuit throughout theoperation of the switch,'and a quick acting relay directly controllingthe release magnet circuit independently of ,said slow-acting relayafter the switch has operated.

63. 1 In a telephone system, a pair of lines, a pair ofautom ticprogressively movable switches operable successively for trunking fromone line to another for setting up a connection between said lines,release means for breaking the connection at each switch, quick relaysand slow relays the system -for controlling said release means, and

means controlled solely through the medium of said quick acting relaysfor operating said release means to break the connection.

64. In a telephone system, a switch, means for releasing the sameincluding a relay slow to release controlling a release magnet duringthe entire setting operation of the switch, a line relay controllingsaid slow relay a quick acting relay controlling the releaseindependently of said slow relay after the switch has operated, andmeans for controlling the two sides of a calling line in series tooperate said switch.

65. In a telephone system, a trunk, a switch for extending connectionthereto, releasing means tor said switch including a slow-acting relaycontrolling the release continuously after the operation of the switchis started and until connection is extended to the trunk, and a quickacting relay controlled over the trunk for controlling the release afterthe switch has established the connection, and means for controlling thetwo .sides of a calling line in series to operatev said switch.

66. In atelephone system, a trunk, a switch for extending connectiontherefrom, releasing means for said switch including a release magnetand a relay slow to release its armature, said relay controlling therelease magnet throughout the time the switch is operating, aquick-acting relay controlling the release magnet independently of saidslow relay. after connection has been established from the trunk, andmeans for controlling the two sides of a calling line in series tooperate said switch.

67'. In a telephone system, a trunk, a switch for selecting said trunkand for extending connection thereto, releasing means for said switchincluding a relay slow to re. lease its armature, said relay controllingthe release during the entire time the switch is operating to selectsaid trunk, and a quick acting relay controlled over said trunk forcontrolling the release of said switch after connection has beenestablished with said trunk- 68. In a telephone system, means includingswitches having selecting motions in two intersecting planes forestablishing a calling connection. means-for releasing the connectionincluding release magnets, circuits for energizing said magnets, slowacting relays controlling the release circuits during the establishmentof the call, and quick acting relays for controlling the releasecircuits during conversation independent of said slow acting relays.

69. In a telephone system, a switch, means for directively operatingsaid switch in a primary movement and for automatically operating saidswitch in a secondary movement, a release magnet for restoring saidswitch, a slow-acting relay controlling said release magnet throughoutthe primary movement of said switch, and a quick acting relaycontrolling said release magnet independent of said slow acting relayafter the secondary movement has been completed.

70. In a telephone system, a line terminating in an automatic switch, aline relay in said switch connected .to said line for controlling theoperation of said switch, a slow acting relay controlled by said linerelay, a release magnet controlled'bysaid slow relay while the switch isoperating, means for disconnecting said line relay from the

